linux-kernel - [PATCH] genirq/irqdesc: Fix deadlock when reading hwirq

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Message-ID: <20250521142541.3832130-1-claudiu.beznea.uj@bp.renesas.com>
Date: Wed, 21 May 2025 17:25:41 +0300
From: Claudiu <claudiu.beznea@...on.dev>
To: tglx@...utronix.de,
	peterz@...radead.org,
	jirislaby@...nel.org
Cc: claudiu.beznea@...on.dev,
	linux-kernel@...r.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH] genirq/irqdesc: Fix deadlock when reading hwirq

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

The &desc->lock is acquired on 2 consecutive lines in hwirq_show(). This
leads to deadlock when reading hwirq. Drop the raw_spin_lock_irq() and
keep guard().

Fixes: 5d964a9f7cd8 ("genirq/irqdesc: Switch to lock guards")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---
 kernel/irq/irqdesc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 6d006a68ff85..b64c57b44c20 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -281,7 +281,6 @@ static ssize_t hwirq_show(struct kobject *kobj, struct kobj_attribute *attr, cha
 	struct irq_desc *desc = container_of(kobj, struct irq_desc, kobj);
 
 	guard(raw_spinlock_irq)(&desc->lock);
-	raw_spin_lock_irq(&desc->lock);
 	if (desc->irq_data.domain)
 		return sysfs_emit(buf, "%lu\n", desc->irq_data.hwirq);
 	return 0;
-- 
2.43.0